Effects Of Phosphorus Application Level On Photosynthesis Characteristics,Yield Of Corn And Soil Phosphorus Fraction

Corn is an important food and feed for our country,and its output affects the balance of grain supply and demand and the development of animal husbandry.Phosphorus is involved in material transformation and energy transfer in crop photosynthesis,and it is an indispensable nutrient during the growth and development of crops,which affecting crop yield and quality.In order to increase the yield of corn,a large amount of phosphate fertilizer was used in the agricultural production,but excessive phosphate fertilizer will not only lead to the waste of phosphorus,but also cause a large amount of phosphorus to be fixed in the soil in a difficult tolerable state,making the crops unable to absorb and use.Therefore,according to the production characteristics of corn in Northeast China,it is of great significance to study the effect of phosphorus application level on corn photosynthesis index,yield and soil phosphorus fraction and soil available phosphorus.In 2016-2019,the experimental settings for four consecutive years without phosphate fertilizer,constant phosphate fertilizer（P₂O₅:80.7 kg/hm²）,high amount of phosphate fertilizer（P₂O₅:161.4kg/hm²）were recorded as P_N,P_C,P_H.Set without phosphorus fertilizer in 2016 and 2017,constant phosphate fertilizer and high amount of phosphate fertilizer in 2018 and 2019 as P_N-C and P_N-H;constant phosphate fertilizer in 2016 and 2017,no phosphate fertilizer in 2018 and 2019 will be recorded as P_C-N;high amount of phosphate fertilizer in 2016 and 2017,without phosphate fertilizer in 2018 and 2019 was recorded as P_H-N.The effects of phosphorus application level on corn light yield,photosynthesis indexes and soil phosphorus components were studied.The result shows:（1）For four consecutive years,without phosphate fertilizer（P_N）,constant phosphate fertilizer（P_C）,and high amount of phosphate fertilizer（P_H）treatment the differences of Fm value P_H and P_Cin each period were not significant,and the tasseling stage was opposite,but all of them were higher than P_N,the Fs value P_H and P_C values of each period were not significant,but the jointing period was opposite,but both were higher than P_N;The Fv/Fm values in each period were not significantly different,and the maturity period was opposite,but both were higher than P_N.In the first two years,without phosphate fertilizer was applied,constant phosphate fertilizer(P_N-C)and high amount of phosphate fertilizer(P_N-H)are applied in the next two years.The Fm,Fs,Fv/Fm values of each period showed an increasing trend with the increase of phosphorus application.The first two years of application of constant phosphate fertilizer and high amount of phosphate fertilizer,and in the next two years without phosphate fertilizer(P_C-N,P_H-N)treatment.The Fm,Fs and Fv/Fm values of each period decreased.（2）For four consecutive years,without phosphate fertilizer（P_N）,constant phosphate fertilizer（P_C）,and high amount of phosphate fertilizer（P_H）treatment were applied.In the third year of implementation,the corn output showed that P_C was higher than P_H and significantly higher than P_N;At four years,maize production showed that P_C was significantly higher than P_H and P_N,P_H was higher than P_N,and the difference was not significant.（3）The first two years without phosphate fertilizer,the next two years of application of constant phosphate fertilizer(P_N-C)and high amount of phosphate fertilizer(P_N-H)treatment will increase the output with the increase of the amount of phosphorus,and resume the first year of phosphorus fertilizer application（2018）The difference is significant,and the difference is not significant in the second year（2019）of resuming the application of phosphate fertilizer.In the first two years,application of constant phosphate fertilizer and high amount of phosphate fertilizer,the first two years（2018-2018）of without phosphate fertilizer(P_C-N,P_H-N)did not show a reduction in production,and the second year（2019）became a reduction trend.（4）For four consecutive years,without phosphate fertilizer（P_N）,constant phosphate fertilizer（P_C）,and high amount of phosphate fertilizer（P_H）treatment the differences of H₂O-P,Na HCO₃-Pi,Na HCO₃-Po,Na OH-Pi,Na OH-Po,Residual-P,total phosphorus P_H and P_C were not significant,but all were higher than P_N,and HCl-P was the opposite.The first two years,without phosphate fertilizer is applied,constant phosphate fertilizer(P_N-C)and high amount of phosphate fertilizer(P_N-H)are applied in the next two years,soil phosphorus fraction showed an increasing trend with the increase of phosphorus application.The first two years,application of constant phosphate fertilizer and high phosphate fertilizer,and in the next two years without phosphate fertilizer(P_C-N,P_H-N)treatment soil phosphorus fraction was reduced.（5）For four consecutive years,without phosphate fertilizer（P_N）,constant phosphate fertilizer（P_C）,and high amount of phosphate fertilizer（P_H）treatment the available phosphorus content in the soil showed no significant difference between P_H and P_C,but both were higher than P_N.The first two years,without phosphate fertilizer was applied,constant phosphate fertilizer(P_N-C)and high amount of phosphate fertilizer(P_N-H)are applied in the next two years treatment the available phosphorus content in the soil showed an increasing trend with the increase of phosphorus application.The first two years,application of constant phosphate fertilizer and high amount of phosphate fertilizer,and in the next two years without phosphate fertilizer(P_C-N,P_H-N)treatment the available phosphorus content in the soil decreased with the increase of phosphorus application.